Imaging system and method for reduction of interstitial images

ABSTRACT

An optical imaging system with a first imaging lens, a field stop, and a second imaging lens configured to reduce the amount of dead space between images of samples.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Ser. No. 10/436,415, filed May 12,2003 which claims priority under 35 U.S.C. § 119(e) to provisionalpatent application No. 60/379,483, filed May 10, 2002, both of which areincorporated herein by reference.

FIELD

The present teachings relate generally to imaging systems and methodsand more particularly to an optical imaging systems for close-packedimaging of interstitially-spaced samples.

INTRODUCTION

Frequently, for example in molecular biology, it is desirable to view orotherwise image individual samples, in order to observe or otherwisedetect changes in the physical state of the sample. Various opticalimaging systems that measure photon flux emitted by samples have beendeveloped. These systems typically comprise groups of lenses to createan image on a charge-coupled display or similar imaging device.

One problem with imaging systems among those in the art is the presenceof interstitial space in the images created. Interstitial space (alsoknown as “dead space”) is the blank area between samples, or the blankspace between the images of the samples. In many instances, theinterstitial space between samples is proportionally larger in size thanthe samples themselves. The presence of interstitial space between theimages of the samples can decrease the overall efficiency of the imagingsystem, for example wasting the capacity of the detector and reducingimage quality. Additionally, the throughput of the imaging system (i.e.,the number of samples that can be processed in a timely fashion) can bereduced.

It is desirable to remove or reduce interstitial space between theimages of the samples. Such removal or reduction can provide moreresolution for the images of a given number of samples, more images ofsamples on a detector of a given capacity, or less area on a detectorfor images of a given number of samples.

SUMMARY

According to various embodiments, an imaging system can comprise aplurality of collection lenses, each lens of the plurality of collectionlenses positioned to receive and collimate light from a plurality ofsamples corresponding to the collection lenses; a first lens systempositioned to receive the collimated light from the plurality ofcollection lenses and focus the collimated light on a primary imagingplane; a second lens system positioned to receive and collimate lightfrom the primary imaging plane; a field stop positioned at the primaryimaging plane to block at least a portion of light from dead spacebetween the plurality of samples; and a detector positioned to detectlight from the second lens system.

According to various embodiments, an imaging system can comprise two ormore samples, wherein the samples have a first dead space between them;a first lens system comprising a first focal length; a second lenssystem comprising a second focal length; a field stop positioned betweenthe first lens system and the second lens system; and a detector,wherein images of the objects are detected, wherein the images have asecond dead space between them; wherein the first lens system, the fieldstop, and the second lens system are positioned between the sample andthe detector; and wherein the second dead space is less than the firstdead space by a factor of second focal length divided by the first focallength.

According to various embodiments, a method for imaging can compriseproviding two or more spaced objects, wherein the objects have a firstdead space between them; positioning a field stop between a first lenssystem and a second lens system; and providing a detector, whereinimages of the objects are detected, wherein the images have a seconddead space between them; wherein the first lens system, the field stop,and the second lens system are positioned between the object and thedetector; and wherein the second dead space is less than the first deadspace.

According to various embodiments, a method for imaging can comprisecollimating light collected from a plurality of samples spaced on asample holder; focusing the collimated light onto a primary image plane;re-collimating the light; and detecting light from each of the pluralityof samples, wherein light from the plurality of samples is substantiallydetected while at least a portion of light from dead space between theplurality of samples is blocked.

Further embodiments and advantages of the present teachings arediscussed below with respect to the following figures. It should beunderstood that the embodiments described herein are examples of thepresent teachings and are intended for purposes of illustration only andare not intended to limit the scope of the teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

According to various embodiments, imaging systems are illustrated inFIGS. 1-10.

FIG. 1 shows a schematic diagram illustrating various embodiments.

FIG. 2 shows a schematic diagram illustrating various embodiments,comprising a plurality of optional focusing lenses.

FIG. 3 shows a schematic diagram illustrating various embodiments,comprising a optional illumination source.

FIG. 4 shows a schematic diagram illustrating various embodiments,comprising a wavelength separation element.

FIG. 5 a shows a perspective view of object regions on a substrateaccording to various embodiments.

FIG. 5 b shows a perspective view of image regions formed on a detectoraccording to various embodiments.

FIG. 6 shows a schematic diagram illustrating various embodiments,without a chromatic separation device.

FIG. 7 shows a schematic diagram illustrating various embodiments,comprising a bandpass filter.

FIG. 8 shows a schematic diagram illustrating various embodiments,comprising a diffraction grating.

FIG. 9 shows a schematic diagram illustrating various embodiments,comprising a prism.

FIG. 10 shows a schematic diagram illustrating various embodiments, withlines representing optical components to show the cropping effect of thefield stop.

It should be noted that the diagrams set forth in these Figures areintended to show the general characteristics of imaging systems inaccordance with the present teachings, for the purpose of thedescription of such embodiments herein. These diagrams are not drawn toscale, may not precisely reflect the characteristics of any givenembodiment, and are not necessarily intended to define or limit specificembodiments within the scope of this invention.

DESCRIPTION OF VARIOUS EMBODIMENTS

According to various embodiments, the imaging system provides highresolution imaging of objects on a platform for use in molecularbiology. The imaging system provides an apparatus that reduces the deadspace between the images of the objects formed on a detector.

According to various embodiments, the imaging system can comprise asample holder, two imaging lenses, two or more collection lenses, afield stop, and a detector. The samples can be distributed on a sampleholder in a variety of ways. Samples can include any material ofinterest in research, including biological materials (such as tissuecells, DNA segments, and other genetic materials), and chemical samples(such as enzymes and other proteins, peptides, and small molecules, suchas from a chemical library, and other chemical samples). (As usedherein, the word “include” and its variants are intended to benon-limiting, such that recitation of items in a list is not to theexclusion of other like items that may also be useful in the materials,compositions, devices, and methods of the present teachings.) The sampleholder can comprise any structure suitable for affixing, containing,holding or otherwise presenting two or more samples in such a mannerthat they can be imaged. A sample holder can comprise structuresincluding containers, holders, wells or other devices that are capableof presenting an individual sample in such a manner that it can beimaged. The samples holder can be constructed of any materials,including at least one of glass, plastic, and composites.

According to various embodiments, the samples on the sample holder canbe disposed in a regular matrix, such that the distance between eachsample along the x-axis and y-axis of the sample holder (i.e., in theplane of the platform perpendicular to the optical axis of the firstimaging lens) can be similar, as illustrated in FIG. 5 a. For example,the sample holder can be a standard 96-well reaction plate. According tovarious embodiments, the sample holder can comprise an irregular matrix,where the x-axis dead space is not equal to the y-axis dead space.According to various embodiments, the sample holder can be formed toaccommodate any collection of samples positioned in any fashion,including rectilinear or curvilinear, as long as the position is knownso that the collection lenses can be positioned to correspond to thesamples.

According to various embodiments, the light provided to the imagingsystem can be reflected light, including light from a source reflectedby the sample or components of the imaging system, scattered light,including light scattered by the sample or components of the imagingsystem, chemiluminescent light, electroluminescent light, and/orfluorescent light, including light emitted by the sample.

According to various embodiments, the imaging system comprises variouslenses and other optical surfaces oriented to project images of thesamples on a detector. Lenses and other optical surfaces among thoseuseful herein are known in the art and are made of various materialsincluding glass (for example, optical glass), quartz, fluorite, rocksalt, plastic, and composites. Optical surfaces, including those oflenses, according to the present teachings can be coated as known in theart to optimize light-reflected or transmitted through the surface ofthe lenses. As further referenced herein; each lens has an object space(which is the spatial region along the optical axis of the lenscontaining the source of light reflected, scattered, and/or emitted froma sample), and an image space (which is the spatial region along theoptical axis of the lens that is opposite of the object space). Eachlens has a focal point and focal plane (the plane perpendicular to theoptical axis of the lens in which the focal point is located). Each lensin the system also has an image plane and object plane which may, or maynot, in the system coincide with the focal planes of the lens. Conceptsamong those underlying the optical devices useful herein are describedin F. Jenkins and H. White, Fundamentals of Optics, 4th ed. (McGraw Hill1976), incorporated by reference herein.

According to various embodiments, the imaging system can comprise any ofa variety of lens types. The lenses can be converging, or positivelenses, which are thicker in the center (along their optical axis) thanat their edges. Such lenses include equiconvex, piano-convex, andpositive meniscus lenses. The lenses may be single lenses, doublets, orother compound lenses. The lenses can be Fresnel lenses, hemisphericallenses, hyper-hemispherical lenses, and/or spherical lenses.

According to various embodiments, FIG. 1 illustrates imaging system (10)comprising a first lens system (13), a second lens system (15), two ormore collection lenses (12), a field stop (14), and a detector (16).According to various embodiments, the first lens and/or second lens canbe a cemented achromatic doublet. The field stop, second imaging lens,and detector can be in the image space (17) of the first lens (13). Thesample holder (11) and the collection lenses (12) can be in the objectspace (18) of the first lens (13). Primary object plane (19) can definethe physical plane of the samples. Primary intermediate image plane (20)can define the visual plane wherein the images of the samples converge.According to various embodiments, the field stop (14) can be positionedat the primary intermediate image plane (20) of the imaging system.Primary image plane (21) can define a visual plane wherein the lighttransmissions can be received by the detector (16), and images of thesamples can be projected.

According to various embodiments, the sample holder (11) comprises aplurality of sample (22) that can be positioned in the object space (18)of the first lens system (13). According to various embodiments, thesecond lens system (15) can be substantially coaxial with the first lenssystem (13) (i.e., they have a common optical axis or optical axes thatare substantially the same).

According to various embodiments, two or more collection lenses (12) canbe positioned in the object space (18) of the first lens system (13).The collection lenses can be molded aspheres. The number of collectionlenses (12) present in the imaging system can be proportionate to, equalto, or substantially equal to the number of samples (22) present in oneimage of the sample holder (11). The collection lenses can be positionedin a plane substantially perpendicular to the primary axis (23) whichcan be the optical axis of the first lens system. The collection lensescan be symmetrically oriented around the primary axis (23). For example,imaging systems comprising an odd number of collection lenses (12), onecollection lens can be coaxial with the primary axis (23), and the othercollection lenses can be positioned in collection plane (24)symmetrically from the primary axis (23) along one or more axes parallelto the primary axis (23). For example, imaging systems comprising aneven number of collection lenses (12), as illustrated in FIG. 1, thecollection lenses can be positioned symmetrically from the primary axis(23) along one or more axes parallel to the primary axis (23). Accordingto various embodiments, collection lenses (12) can be distributed asneeded to collect light from samples (22) without regard to thedistribution of collection lenses (12) around primary axis (23).According to various embodiments, as illustrated in FIG. 10, collectionlenses (12) can provide collimated light (130) originating from objects(22). Collimated light (130) can be parallel with primary axis (23).According to various embodiments, collection lenses (12) can bepositioned in collection plane (24) that can be perpendicular to primaryaxis (23). According to various embodiments, collection lenses (12) canbe positioned to provide collimated light (130) parallel to primary axis(23).

According to various embodiments, imaging system (10) comprises a fieldstop (14). The field stop can be positioned between the first lenssystem (13) and the second lens system (15). The field stop can bepositioned at primary intermediate image plane (20). According tovarious embodiments, primary intermediate plane image (20) can be thefocal plane of the first lens system (13). According to variousembodiments, field stop (14) can be positioned at a plane that is thecommon focal plane of the first lens system (13) and second lens system(15). The field stop (14) can be configured to have a size and shape toblock light rays emanating from the dead space between samples (22) onsample holder (11).

According to various embodiments, the field stop can comprise anyopening that passes light emanating from the samples while blocking atleast some of the light emanating from the dead space between thesamples. According to various embodiments, the field stop can be aspatial filter. According to various embodiments, the field stop can bea slit comprising two substantially parallel edges. According to variousembodiments, the field stop can be the shape of a square or otherparallelogram. According to various embodiments, the field stop can becurved, circular, oval, and/or elliptical. According to variousembodiments, the field stop can be a pin hole.

According to various embodiments, as illustrated in FIG. 1, imagingsystem (10) can be characterized as having a plurality of opticalchannels (25). Each optical channel (25) comprises the optics fortransmission of light from each sample (22) onto detector (16). Thus,the number of optical channels (25) is equal to the number of samples(22) imaging system (10) can image. Image (200) on detector (16) can becharacterized as comprising a group or bundle of light rays originatingfrom a single sample. Each optical channel (25) can comprise one of thecollection lenses (12), the first lens system (13), the field stop (14),and the second lens system (15). According to various embodiments, alight bundle from each sample (22) can travel through and can becollimated by one of the collection lenses (12). The bundle then travelsthrough first lens system (13) and can be focused onto primaryintermediate image plane (20) where the field stop (14) is positioned.After exiting the field stop (14), each of the light bundles can travelto the second lens system (15), and can be collimated as they pass todetector (16).

According to various embodiments, the imaging system can compriseoptical components that enhance or otherwise affect the manner in whichthe image is formed, transmitted or detected. Such optical elementsinclude lenses, mirrors, light sources, filters, dispersive elements,and detectors. As illustrated in FIG. 2, various embodiments cancomprise two or more focusing lenses (30) in image space (31) of thesecond lens system (15), between second lens system (15) and detector(16). Each focusing lens (30) can form an image (200) of sample (22)onto detector (16). Without the focusing lenses (30), the collimatedbeams from second lens system (15) can be projected onto detector (16)as an array of light beams, as illustrated in FIG. 1. The focusinglenses (30) can focus the image (200) of sample (22) on detector (16).As illustrated in FIG. 2, each of the optical channels (25) of theimaging system (10) can comprise one of collection lenses (12), firstlens system (13), field stop (14), second lens system (15), and one offocusing lenses (30).

According to various embodiments, the optical imaging system cancomprise a light source, for illuminating the samples in the sampleholder. As illustrated in FIG. 3 a, imaging system (10) can compriseoptical components for illuminating samples along primary axis (23).Light source (40) can be positioned along an axis (41) that intersectswith, and can be substantially perpendicular to, primary axis (23). FIG.3 a illustrates beam splitter (42), including a dichroic mirror,positioned in the region of collimated light (130) between collectionlenses (12) and first lens system (13). A collimating lens (43) can bepositioned between light source (40) and beam splitter (42). Beamsplitter (42) can be a dichroic reflective surface or mirror that canreflect light at a wavelength illuminated by light source (40) towardsamples (22), and can transmit light emitted at a different wavelengthfrom samples (22) to the remaining components of the imaging system(10).

According to various embodiments, illumination can be positioned atother points in the system. For example, illumination can be positionedto intersect at primary intermediate image plane (20) wherein field stop(14) can be positioned. As illustrated in FIG. 3 b, illumination source(50) can be positioned along the primary intermediate image plane (20)or an axis parallel that is substantially perpendicular to the primaryaxis (23). Illuminating light can enter the primary axis (23) at beamsplitter (51) positioned in front of, at, or beyond the primaryintermediate image plane (20). Illuminating light can converge to afocus that is conjugate to the primary intermediate image plane. Thefield stop (14) can be positioned at the primary intermediate imageplane (20) coincident with the beam splitter (51). According to variousembodiments, illumination source (50) can be collimated, for example alaser light source. Third lens system (52) can be positioned along theaxis of the illumination (19), between illumination source (50) and beamsplitter (51) to focus the collimated light.

According to various embodiments, the imaging system can comprise achromatic separation component for modifying the spectral properties ofthe images of the samples. Such a chromatic separation component caninclude filter wheels, prisms, gratings, or various other dispersive andfiltering elements. The chromatic separation device can separate thelight from the image into its spectral components. The chromaticseparation device can operate via dispersion, diffraction, and/orfiltering. FIG. 4 illustrates an imaging system comprising a chromaticseparation component (60) between second lens system (15) and detector(16). FIG. 6 illustrates an imaging system comprising focusing lenses(30) without a chromatic separation component. FIG. 7 illustrates animaging system comprising a bandpass filter (70) as a chromaticseparation component positioned between second lens system (15) andfocusing lenses (30). A filter component, such as bandpass filter (70),can provide specific wavelengths of light to the detector (not shown)while filtering out others to provide chromatic separation. FIG. 8illustrates an imaging system comprising a grating (80) as a chromaticseparation device positioned between second lens system (15) andfocusing lenses (30). A diffractive component, such as grating (80), canprovide diffraction to the light from second lens system (15) to providechromatic separation. Focusing lenses (30) can be positioned to focusspecific wavelengths of light onto the detector (not shown). FIG. 9illustrates an imaging system comprising a prism (90) as a chromaticseparation device positioned between second lens system (15) andfocusing lenses (30). A dispersive component, such as prism (80), canprovide dispersion to the light from second lens system (15) to providechromatic separation. Focusing lenses (30) can be positioned to focusspecific wavelengths of light to the detector (not shown). According tovarious embodiments, imaging systems using gratings or prisms for colorseparation can provide spatial information in one dimension on thedetector and spectral information in the other dimension.

According to various embodiments, the imaging system can remove orreduce dead space between the images of the samples. Such removal orreduction can provide increased resolution for the images of a givennumber of samples, more images of samples on a detector of a givencapacity, or less area on a detector for images of a given number ofsamples. According to various embodiments, the detector can be acharged-coupled device (CCD) or other pixilated image sensor. As knownin the art, CCD detectors comprise pixels for imaging. The imaging areaof the CCD detector can provide a number of pixels. According to variousembodiments, removing or reducing the dead space imaged on the CCDdetector can provide additional pixels for increasing resolution for theimages of a given number of samples, i.e., dedicating more pixels persample image. According to various embodiments, removing or reducing thedead space imaged on the CCD detector can provide additional pixels forimaging more samples on the pixels provided by the CCD detector.According to various embodiments, removing or reducing the dead spaceimaged on the CCD detector can provide surplus pixels justifying the useof a CCD detector with a smaller imaging area that provides less pixels.

According to various embodiments, FIG. 5 a illustrates a top view ofsample holder (11) comprising a plurality of samples (22). Each sampleto be imaged can have a 2 H by 2 H dimension. The samples (22) can bepositioned a certain distance apart, represented by the value, Δ. Thevalue, Δ, is known as interstitial space or dead space (110) betweeneach sample (22) to be imaged. According to various embodiments, thevalue, Δ, can be much larger than 2 H. According to various embodiments,an imaging system comprising collection lenses, a first lens system, afield stop, and a second lens system can reduce the interstitial spaceor dead space between the images (200) of the samples projected ondetector (16) to the value, δ, where δ is less than Δ. According tovarious embodiments, an imaging system comprising collection lenses, afirst lens system, a field stop, and a second lens system can reduce thedimensions of the images (200) of the samples to 2 h by 2 h. FIG. 5 billustrates detector (16) where the dead space between images (200) ofsamples can be 6 and the dimension of images (200) of samples can be 2h. The imaging system can provide a ratio δ/Δ that is less than theratio h/H. It should be noted that the values of H, Δ, h, and δ canvary, depending on the sample holder, the specific samples to be imaged,and the optical components of the imaging system.

According to various embodiments, each of the lenses of the imagingsystem can be characterized by their focal lengths. FIG. 2 illustratesan imaging system comprising collection lenses (12) wherein each canhave a focal length, f3, first lens system (13) that can have a focallength, f1, second lens system (15) that can have a focal length, f2,and focusing lenses (30) wherein each can have a focal length, f4. Thecombination and orientation of these lenses can determine the amount ofreduction in the dead space between the images of the samples.

According to various embodiments, an imaging system can accommodate thedead space (110) between each of the samples (22) that can have a valueof Δ by providing lenses with focal lengths that can provide a desiredamount of dead space reduction between the images (200) of samples. Thedead space between the images (200) of samples on the detector (16) thatcan have a value of δ that relates to the dead space (110) between thesamples (22) that can have the value A according to the ratio of f2 tof1, according to formula (A): $\begin{matrix}{\delta = {\frac{f_{2}}{f_{1}}\Delta}} & (A)\end{matrix}$

According to various embodiments, an imaging system can providereduction in the dimensions of images (200) of samples represented by hcan be reduced by a ratio function of f1 through f4. The imaging systemcan modify the dimension of samples (22) represented by H to thedimension of the images (200) of the samples represented by h accordingto formula (B): $\begin{matrix}{h = {\frac{f_{1} \times f_{4}}{f_{2} \times f_{3}}H}} & (B)\end{matrix}$

According to various embodiments, an imaging system can comprise a fieldstop to reduce the dead space between the images (200) of the samples.The field stop blocks the dead space around the images of the samples toreduce or eliminate the dead space between the images (200) of thesamples. The field stop blocks the dead space between the images (200)of the samples according formula (A). As illustrated in FIG. 10, samples(22) from samples holder (11) can provide light (120) that can becollimated by collection lenses (12) to form collimated light (130).Collimated light (130) can be focused by first lens system (13) onto theopening of field stop (14). Dead space (110) between samples (22) canprovide light (140). Light (140) can avoid collection lenses (12) andcan avoid being collimated. Light (140) that is not collimated can avoidbeing focused onto the opening of field stop (14) and can be blockedportions (150) of field stop (14). The field stop (14) can therebyreduce light (140) from dead space (110) between samples (22) that canreach the detector. According to various embodiments, light (140) can beblocked by a mask corresponding to the gaps between collection lensesand can avoid being focused onto the opening of field stop (14).

According to various embodiments, it is desirable to avoid superimposingthe dead space surrounding one sample on the image of the adjacentsample and vice versa. The field stop can reduce cross-over of theimages of the samples.

According to various embodiments, a method for imaging can compriseproviding two or more samples, wherein the samples have a first deadspace between them; positioning a field stop between a first lens systemand a second lens system; and providing a detector, wherein images ofthe samples are detected, wherein the images have a second dead spacebetween them; wherein the first lens system, the field stop, and thesecond lens system are positioned between the samples and the detector;and wherein the second dead space is less than the first dead space. Themethod can further comprise positioning the first lens system and thesecond lens system such that both their image planes coincide with thefield stop.

According to various embodiments, a method for imaging can comprisecollimating light collected from a plurality of samples spaced on asample holder; focusing the collimated light onto a primary image plane;re-collimating the light; and detecting light from each of the pluralityof samples, wherein light from the plurality of samples is substantiallydetected while at least a portion of light from dead space between theplurality of samples is blocked. The method can further comprisespatially filtering light near the primary image plane. The term “near”as used herein refers to at or substantially proximate to the plane.

EXAMPLE

According to various embodiments, the dimensions and materialsassociated with an example of the optical imaging system are describedin the following Table 1. Table 1 describes the positioning and featuresof the optical elements. Optical elements are defined in order in thesystem, from object to detector, including distances between elements.TABLE 1 Curvature Aperture Distance to next radius Radius component/Optical Element (mm) (mm) Material surface (mm) object — 100 — 13.72collection lens 0 3.00 CO550 2.20 surface 1 collection lens −9.13 3.00 —89.55 surface 2 first lens surface 1 47.90 23.25 BAK4 13.5 first lenssurface 2 −41.60 23.25 SF10 C 5.25 first lens surface 3 −129.63 23.25 —64.53 field stop — 25.00 air 43.02 second lens 86.43 15.50 SF10 C 3.50surface 1 second lens 27.73 15.50 BAK4 9.00 surface 2 second lens −31.9415.50 — 70.50 surface 3 focusing lens 18.26 2.65 CO550 2.20 surface 1focusing lens 0 3.00 — 29.37 surface 2 detector — — — —Table 1 describes an imaging system comprising a collection lens, afirst lens system, a field stop, a second lens system, and a focusinglens between the sample and the detector. The collection lens is apiano-convex lens, the first imaging lens is a cemented doublet, thesecond imaging lens is a cemented doublet, and the focusing lens is aplano-convex lens. The last column in Table 1, Distance to nextcomponent/surface in millimeters represents distances between opticalcomponents (e.g., 13.72 mm between the sample and the first surface ofthe collection lens), or distance between surfaces of a lens (i.e.,thickness of lens; e.g., the collection lens is 2.20 mm thick). The restof Table 1 describes the curvature radius in millimeters (i.e. positivevalues represent curvature towards the detector and negative valuesrepresent curvature towards the sample), the aperture radius (e.g. theradius of the lens or the length of the field stop), and the materialcomposition of the optical components through which light passes.

The example and other embodiments described herein are exemplary and notintended to be limiting in describing the full scope of optical systemsof this invention. Equivalent changes, modifications and variations ofspecific embodiments, materials, compositions and methods may be madewithin the scope of the present invention, with substantially similarresults.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages, orother numerical values used in the specification and claims, are to beunderstood as being modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired propertiessought to be obtained by the present invention. At the very least, andnot as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all subranges subsumedtherein. For example, a range of “1 to 10” includes any and allsubranges between (and including) the minimum value of 1 and the maximumvalue of 10, that is, any and all subranges having a minimum value ofequal to or greater than 1 and a maximum value of equal to or less than10, e.g., 5.5 to 10.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” include plural referents unlessexpressly and unequivocally limited to one referent. Thus, for example,reference to “a lens” includes two or more lenses.

1. An imaging system, comprising: a plurality of collection lenses, eachlens of the plurality of collection lenses positioned to receive andcollimate light from a plurality of samples corresponding to thecollection lenses; a first lens system positioned to receive thecollimated light from the plurality of collection lenses and focus thecollimated light on a primary imaging plane; a second lens systempositioned to receive and collimate light from the primary imagingplane; a field stop positioned at the-primary imaging plane to block atleast a portion of light from dead space between the plurality ofsamples; and a detector positioned to detect light from the second lenssystem.
 2. A system according to claim 1, wherein the field stop is inan image plane of the first lens system.
 3. A system according to claim2, wherein the field stop is in an image plane of the second lenssystem.
 4. A system according to claim 3, further comprising a sampleholder for holding the plurality of samples.
 5. A system according toclaim 4, further comprising a plurality of focusing lenses correspondingto the plurality of samples and positioned between the second lenssystem and the detector.
 6. A system according to claim 5, comprising aplurality of optical channels, each channel comprising one of theplurality of collection lenses, the first imaging lens, the secondimaging lens, the field stop, one of the plurality of focusing lenses,and the detector.
 7. A system according to claim 1 wherein the fieldstop is a slit comprising two substantially parallel edges.
 8. A systemaccording to claim 1, further comprising a light source.
 9. A systemaccording to claim 8, further comprising a beam splitter positionedbetween the plurality of collection lenses and the first lens system.10. A system according to claim 8, further comprising a beam splitterpositioned prior to, coincident with, or past the field stop.
 11. Asystem according to claim 3, further comprising a chromatic separationdevice positioned between the second lens system and the detector.
 12. Amethod for imaging, comprising: collimating light collected from aplurality of samples spaced on a sample holder; focusing the collimatedlight onto a primary image plane; blocking at least a portion of lightfrom dead space between the plurality of samples; re-collimating thelight; and detecting light from each of the plurality of samples.
 13. Amethod according to claim 12, further comprising spatially filteringlight near the primary image plane.
 14. A method according to claim 12,wherein said blocking comprises blocking with a field stop.
 15. A methodaccording to claim 12, wherein said blocking comprises blocking with amask.